Electrical outlet boxes are widely used in the construction industry for providing access to electric power in homes, office buildings and factories. The outlet boxes are constructed in a number of sizes, generally in accordance with industry standards to support the desired number of wiring devices at any given wall location. The boxes are also constructed with a sufficient volume to permit termination of the cable conductors to the desired wiring devices to provide access to electric power throughout the building. In order accommodate the dual functions of providing a power outlet as well as the joining of wires, the outlet boxes are provided, in accordance with an industry standard, with a predetermined number of cable entry ports by which the wires are brought into and out of the outlet box.
To facilitate deployment of the outlet boxes, the cable entry ports are provided with closure means to prevent the entry of debris when the ports are not used. In the case of a metal box, partially attached discs close the ports but are readily removable from the box by a sharp blow or a prying tool. In the case of molded plastic boxes, each port may be closed with a removable panel member which is attached to the rim of the ports.
Recently, Slater Electric Inc. (the assignee of the present application) has developed a new closure structure for moldable electrical outlet boxes, which not only closes the unused port but also permits easy opening by the force exerted by a cable and can provide automatic clamping of the cable when inserted through the port. These structures are disclosed in commonly assigned co-pending applications Ser. Nos. 879,767 (filed Feb. 21, 1978), 22,993 (filed Mar. 22, 1979) and 200,422 (filed Oct. 24, 1980), which are hereby incorporated by reference.
The aforesaid structures are easily molded and can provide a unique integrally formed outlet box. Thus, it is highly desirable to incorporate such structures in all the ports of various size outlet boxes. One problem can arise in realizing this desire.
In order to provide such structures, particularly the self-clamping type structure, adjacent each cable entry port, there must be sufficient structural strength in the immediately adjacent wall structure to withstand the cable-clamping forces that will be transmitted to the wall by the panel member(s) making up the closure structure. In addition, there may be a physical problem in that there might not be enough surface area in the wall to accommodate such closure structures in all the cable entry ports formed in the wall.
Accordingly, it is an object of the present invention to provide a new and improved outlet box structure adapted to permit incorporation of the aforesaid improved cable entry port closure structures at every entry port in any single wall of the outlet box, while satisfying industry standards for the size of the ports, the strength of the closure structures, etc.